High n-3 HUFA levels in the diet of Atlantic salmon affect muscle and mitochondrial membrane lipids and their susceptibility to oxidative stress

Abstract

Atlantic salmon were fed one of four diets with increasing levels (11–58%of total fatty acids (FAs)) of n‐3 highly unsaturated FAs (HUFAs) in order to investigate the effect on muscle and mitochondrial membrane lipids and their susceptibility to oxidative stress. The high n‐3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) groups contained lower percentages of sphingomyelin and cardiolipin in total muscle than the intermediate n‐3 HUFA group. Cardiolipin and sphingomyelin are particularly susceptible to peroxidation, and a reduced percentage of these lipids showed that mitochondrial membranes had been damaged by oxidation. The intermediate n‐3 HUFA group had the highest level of mitochondrial integrity and tendencies of lower thiobarbituric acid reactive substances (TBARS) level than the other dietary groups. The high caspase‐3 activity, in addition to casp3a and bax gene expression levels, in the n‐3 DHA group also suggests that some degree of oxidative stress had occurred. Electron microscopy images showed a higher degree of myofibre–myofibre detachment in fish fed the high HUFA diets than in fish fed the intermediate n‐3 HUFA diet. Our findings show that intermediate levels of n‐3 HUFAs in salmon diets gave the best protection against oxidative damage of mitochondrial membranes and muscle structure.

Dietary fatty acids affect mitochondrial phospholipid compositions and mitochondrial gene expression of rainbow trout liver at different ages

“…These data agree with those showing marked modifications of FA of total mitochondrial PL by diet in rats (Lemieux et al 2008;Abbott et al 2010) and fish (Ushio et al 1997;Robin et al 2003;Guderley et al 2008;Østbye et al 2011;Martin et al 2013), and indicates the existence of mechanisms regulating FA within mitochondrial PL classes. Moreover, these data point to the importance of FA composition of specific PL classes in mitochondrial membranes.…”

“…Another explanation may be an increase in the degree of oxidative stress and, particularly, lipid peroxidation that would decrease membrane levels of PUFAs ). The observed decrease in mitochondrial total PL content in RO and especially, DHA groups could indicate the existence of high oxidative stress as was found in liver and muscle mitochondria of Atlantic salmon fed diets with a high level of n-3 LC-PUFA (Kjaer et al 2008;Østbye et al 2011). These studies also showed a decrease in CL content in mitochondrial membranes that agrees with data in the present study.…”

“…The aim of the present study was to determine the impact of diet lipid composition on mitochondrial membrane composition and mtDNA damage as possible regulators of the processes associated with mitochondrial decay under high oxidative stress situations in fish. Rainbow trout (Oncorhynchus mykiss) was used as a vertebrate model because it is a wellstudied species, widely reared in Europe, its age can be easily monitored (Almroth et al 2010) and, along with other species of salmonids, it has been used previously in studies on dietary lipid, oxidative stress, and mitochondrial function (Otto and Moon 1996;Zabelinskii et al 1999;Kraffe et al 2007;Østbye et al 2011). For the present study, fish of two well-differentiated ages (fast growth period and mature period) were used in order to study the influence of fish age and body mass on these mechanisms.…”

Effects of dietary fatty acids on mitochondrial phospholipid compositions, oxidative status and mitochondrial gene expression of zebrafish at different ages

“…This theory would explain the huge differences in life The present data showed that mitochondria from 8-month-old zebrafish fed the DHA diet had higher levels of n-3 LC-PUFA and higher peroxidation index (PIn) value in the three main phospholipid classes, phosphatidylcholine (PC), phosphatidylethanolamine (PE) and cardiolipin (CL) (changes in PIn only significant for PE). These data are consistent with those showing considerable dietary modifications of FA composition of mitochondrial PL in rats (Lemieux et al 2008;Abbott et al 2010) and fish (Ushio et al 1997;Robin et al 2003;Guderley et al 2008;Ostbye et al 2011;Martin et al 2013;Almaida-Pagán et al 2015). However, they also indicate the existence of regulatory mechanisms of specific fatty acids within mitochondrial membranes as the observed changes did not clearly reflect the dietary compositions.…”

“…Lipid peroxidation in total lipid from mitochondria was double in fish fed the DHA diet than in fish fed the RO diet in 8-month-old fish. This indicated higher oxidative damage to mitochondrial lipids in young zebrafish fed the DHA diet, very likely due to the higher incorporation of long-chain polyunsaturated fatty acids (LC-PUFA), particularly DHA, in PL of mitochondrial membranes in fish fed diet DHA compared to fish fed the RO diet, as shown previously in liver and muscle mitochondria of Atlantic salmon, Salmo salar (Kjaer et al 2008;Ostbye et al 2011) and in liver mitochondria of rainbow trout (Oncorhynchus mykiss; Almaida-Pagán et al 2015). Several studies indicated that increase in dietary PUFA elevated the metabolic rate which would be very likely mediated by changes in membrane composition .…”